System and method for downhole telemetry

Abstract

A system and method are provided for providing electromagnetic (EM) measurement-while-drilling (MWD) telemetry capabilities using an existing mud-pulse MWD tool. An EM tool intercepts the output from the mud-pulse tool and generates an EM signal that mimics a mud-pulse pressure signal. The EM signal is intercepted at the surface by a receiver module that conditions the signal and inputs the signal into the existing pulse tool receiver. Since the EM signal mimics a mud-pulse signal, the pulse tool receiver does not require software or hardware modifications in order to process an EM telemetry mode. The EM tool can be adapted to also provide dual telemetry by incorporating a conventional pressure pulser that would normally be used with the pulse tool.

The invention claimed is: 
     
       1. A dual telemetry measurement while drilling tool string, the tool string comprising a plurality of modules interconnected lengthwise to enable the tool string to be deployed within a drill string, the plurality of modules comprising:
 a directional module operable to obtain data from at least one sensor; 
 an electromagnetic transmitter module operable to receive a first data input representative of the data obtained by the directional module from the at least one sensor, and operable to send an electromagnetic signal through an earth formation using an electromagnetic signal generated using the first data input; 
 a mud pulse module operable to receive a second data input representative of the data obtained by the directional module from the at least one sensor, and operable to use the second data input to have a series of pulses transmitted through a mud column in the drill string; and 
 at least one battery module for powering the directional module, the electromagnetic transmitter module, and the mud pulse module. 
 
     
     
       2. The tool string of  claim 1 , further comprising a first connection between the tool string and an inner wall of the drill string on one side of a region of isolation of the drill string and a second connection between the tool string and the inner wall of the drill string on the other side of the region of isolation. 
     
     
       3. The tool string of  claim 2 , the first and second connections comprising components extending from the tool string and contacting the inner wall of the drill string. 
     
     
       4. The tool string of  claim 3 , the components comprising at least one flexible member to engage the inner wall of the drill string. 
     
     
       5. The tool string of  claim 4 , the at least one flexible member comprising a pair of bow springs. 
     
     
       6. The tool string of  claim 1 , further comprising a landing bit for positioning the tool string within the drill string. 
     
     
       7. The tool string of  claim 6 , the landing bit further comprising a mud pulse value used by the mud pulse module for generating the series of pulses in the mud column. 
     
     
       8. The tool string of  claim 1 , capable of being operated to selectively provide any one or more of the first data input and the second data input. 
     
     
       9. The tool string of  claim 1 , the electromagnetic transmitter module being configured to interface with any one or more of a commercially available mud pulse module and a commercially available directional unit module. 
     
     
       10. The tool string of  claim 1 , the directional module capable of receiving at least one instruction from a surface controller. 
     
     
       11. The tool string of  claim 1 , wherein the electromagnetic transmitter module is positioned in the tool string to be aligned with a region of isolation in the drill string. 
     
     
       12. A dual telemetry measurement while drilling system, the system comprising:
 a tool string comprising a plurality of modules interconnected lengthwise to enable the tool string to be deployed within a drill string, the plurality of modules comprising: 
 a directional module operable to obtain data from at least one sensor; 
 an electromagnetic transmitter module operable to receive a first data input representative of the data obtained by the directional module from the at least one sensor, and operable to send an electromagnetic signal through an earth formation using an electromagnetic signal generated using the first data input; 
 a mud pulse module operable to receive a second data input representative of the data obtained by the directional module from the at least one sensor, and operable to use the second data input to have a series of pulses transmitted through a mud column in the drill string; and 
 at least one battery module for powering the directional module, the electromagnetic transmitter module, and the mud pulse module; and 
 at least one drill string component to be incorporated into the drill string for providing a region of isolation in the drill string. 
 
     
     
       13. The system of  claim 12 , further comprising a modified universal bottom hole offset (UBHO) component incorporated into the drill string to align the tool string and the region of isolation. 
     
     
       14. The system of  claim 12 , further comprising at least one surface receiver for obtaining data signals transmitted by the tool string. 
     
     
       15. The system of  claim 12 , further comprising a first connection between the tool string and an inner wall of the drill string on one side of a region of isolation of the drill string and a second connection between the tool string and the inner wall of the drill string on the other side of the region of isolation. 
     
     
       16. The system of  claim 15 , the first and second connections comprising components extending from the tool string and contacting the inner wall of the drill string. 
     
     
       17. The system of  claim 16 , the components comprising at least one flexible member to engage the inner wall of the drill string. 
     
     
       18. The system of  claim 17 , the at least one flexible member comprising a pair of bow springs. 
     
     
       19. The system of  claim 12 , further comprising a landing bit for positioning the tool string within the drill string. 
     
     
       20. The system of  claim 19 , the landing bit further comprising a mud pulse value used by the mud pulse module for generating the series of pulses in the mud column. 
     
     
       21. The system of  claim 12 , the tool string capable of being operated to selectively provide any one or more of the first data input and the second data input. 
     
     
       22. The system of  claim 12 , the electromagnetic transmitter module being configured to interface with any one or more of a commercially available mud pulse module and a commercially available directional unit module. 
     
     
       23. The system of  claim 12 , the directional module capable of receiving at least one instruction from a surface controller. 
     
     
       24. The system of  claim 23 , the surface controller being independent of at least one surface receiver used to obtain data signals transmitted by the tool string. 
     
     
       25. The system of  claim 12 , wherein the electromagnetic transmitter module is positioned in the tool string to be aligned with the region of isolation in the at least one drill string component. 
     
     
       26. A method of operating a dual telemetry measurement while drilling tool string comprising a plurality of modules interconnected lengthwise to enable the tool string to be deployed within a drill string, the plurality of modules comprising a directional module operable to obtain data from at least one sensor, an electromagnetic unit, a mud pulse unit, and at least one battery module for powering the directional module, the electromagnetic unit, and the mud pulse unit, the method comprising:
 obtaining, at the directional module, the data from the at least one sensor, and providing the data to at least one of the electromagnetic unit and the mud pulse unit; 
 during operation of the electromagnetic unit:
 receiving, at an electromagnetic transmitter module, a first data input representative of the data obtained by the directional module from the at least one sensor; 
 the electromagnetic transmitter sending an electromagnetic signal through an earth formation using according to the first data input, the electromagnetic transmitter module being positioned in the tool string to be aligned with a region of isolation in the drill string; and 
 
 during operation of the mud pulse unit:
 receiving, at a mud pulse module, a second data input representative of the data obtained by the directional module from the at least one sensor; and 
 the mud pulse module using the second data input to have a series of pulses transmitted through a mud column in the drill string. 
 
 
     
     
       27. The method of  claim 26 , further comprising receiving an instruction from a surface system to operate in one or more of an electromagnetic telemetry mode and a mud pulse telemetry mode. 
     
     
       28. The method of  claim 26 , further comprising receiving a transmitted signal at a surface receiver, the transmitted signal being detected from the electromagnetic signal or the series of pulses. 
     
     
       29. A method of assembling a measurement while drilling system to provide dual telemetry capabilities, the method comprising:
 assembling a tool string using a plurality of modules interconnected lengthwise, the plurality of modules comprising a directional module operable to obtain data from at least one sensor, a mud pulse module operable to provide mud pulse telemetry of the data, an electromagnetic transmitter module operable to transmit an electromagnetic signal representing the data, and at least one battery module for powering the directional module, the electromagnetic transmitter module, and the mud pulse module, the electromagnetic transmitter module operable to receive a first data input representative of the data obtained by the directional module from the at least one sensor and operable to send an electromagnetic signal through an earth formation using an electromagnetic signal generated using the first data input, the mud pulse module operable to receive a second data input representative of the data obtained by the directional module from the at least one sensor and operable to use the second data input to have a series of pulses transmitted through a mud column in the drill string; 
 assembling at least one drill string component into a drill string to provide a region of isolation in the drill string; and 
 locating the tool string in the drill string such that the electromagnetic transmitter is operably aligned with the region of isolation. 
 
     
     
       30. The method of  claim 29 , wherein a modified universal bottom hole offset (UBHO) component is incorporated into the drill string to align the tool string and the region of isolation. 
     
     
       31. The method of  claim 29 , further comprising making a first connection between the tool string and an inner wall of the drill string on one side of the region of isolation of the drill string, and a second connection between the tool string and the inner wall of the drill string on the other side of the region of isolation. 
     
     
       32. The method of  claim 31 , the first and second connections comprising components extending from the tool string and contacting the inner wall of the drill string. 
     
     
       33. The method of  claim 32 , the components comprising at least one flexible member to engage the inner wall of the drill string. 
     
     
       34. The method of  claim 33 , the at least one flexible member comprising a pair of bow springs. 
     
     
       35. The method of  claim 29 , further comprising connecting a landing bit to the tool string for positioning the tool string within the drill string. 
     
     
       36. The method of  claim 35 , the landing bit further comprising a mud pulse value used by the mud pulse module for generating the series of pulses in the mud column.